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<TITLE>Magic-7.3 Command Reference</TITLE>
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<H1> <IMG SRC=graphics/magic_title2.gif ALT="Magic VLSI Layout Tool Version 7.3">
     <IMG SRC=graphics/magic_OGL_sm.gif ALIGN="top" ALT="*"> </H1>

<H2>snap</H2>
<HR>
Cause box to snap to the selected grid when moved by the cursor.  Also,
cause distance measurements to be interpreted by default as measurments
in the selected grid.
<HR>

<H3>Usage:</H3>
   <BLOCKQUOTE>
      <B>snap</B> [<B>internal</B>|<B>lambda</B>|<B>user</B>] <BR><BR>
   </BLOCKQUOTE>

<H3>Summary:</H3>
   <BLOCKQUOTE>
      The <B>snap</B> command causes the cursor box to snap to the
      selected grid when moved by pointer button events.  The selected
      grids are <B>internal</B>, the size of the internal database,
      <B>lambda</B>, the lambda grid based on the technology minimum
      feature size, and <B>user</B>, based on the value given by the
      user to the <B>grid</B> command. <P>

      In addition to changing the behavior of the box to mouse
      button events, the <B>snap</B> command also changes the way
      that <A HREF=distance.html>distance measurements</A> are
      interpreted in commands that take distance arguments, such
      as <B>move</B>, <B>copy</B>, and <B>stretch</B>.  An integer
      number with no other identifying units is interpreted as a
      measurement in the current snap grid.  All other measurements
      must have an identifying unit: <B>i</B> for internal units,
      <B>l</B> for lambda units, and <B>g</B> for user grid units
      (as well as the usual metric units).  Even when <B>snap</B>
      is set to the larger lambda or user grids, it is possible to
      move the cursor box to finer grid positions from the command
      line.  See the reference page on
      <A HREF=distance.html>distance measures</A> for a complete
      description of distance values. <P>

      <B>snap</B> with no arguments returns the current snap grid
      type. <P>

      By default, the internal and lambda grids are the same.  However,
      CIF, GDS, or LEF/DEF input on a finer scale can cause the internal
      grid to be set finer than the lambda grid.  Also, the <B>scalegrid</B>
      command can be used to separate the internal and lambda grids.
      Note that the use of "lambda" is merely a convention.  Traditionally,
      scalable CMOS rules were based on units of "lambda", equal to
      one-half the minimum feature size of the technology.  Many
      technology files are still based on lambda rules, which are usually
      more conservative than vendor rules.  However, some technology files
      may be based on exactly implementing vendor rules, and may set
      the internal grid spacing to a finer resolution, such as 0.1 micron
      or smaller.  In such cases, the use of the term "lambda" is a
      misnomer.
   </BLOCKQUOTE>

<H3>Implementation Notes:</H3>
   <BLOCKQUOTE>
      <B>snap</B> is implemented as a built-in command in <B>magic</B>.
   </BLOCKQUOTE>

<H3>See Also:</H3>
   <BLOCKQUOTE>
      <A HREF=grid.html><B>grid</B></A> <BR>
   </BLOCKQUOTE>

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<P><I>Last updated:</I> October 8, 2004 at 7:16am <P>
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